JP2009289449A - Induction heating cooker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an induction heating cooker capable of heating a pan of high electric conductive material in which there is less heating variations, and reduction of heating efficiency is suppressed while reducing buoyancy acted on the pan. <P>SOLUTION: The induction heating cooker includes a heating coil capable of induction-heating the pan 19 which is a heated material composed of aluminum or copper or low magnetic permeability material having conductivity equal to or more than that of these, an inverter circuit 6 to supply high-frequency wave current to the heating coil, and an annular electric conductor plate which is installed between the heating coil and the pan so as not to cover the center part of the heating coil or its vicinity, and includes a slit part from its outer diameter up to its inner diameter. The heating coil is divided into two with a spacing between the inner heating coil 13 and the outer heating coil 14, the annular electric conductor plate is also divided into two with a spacing between the inner annular electric conductor plate 16 and the outer annular electric conductor plate 17, and a gap part of the inner annular electric conductor plate 16 and the outer annular conductor plate 17 is installed above the spacing part of the inner heating coil and the outer heating coil. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an induction heating cooker used in general homes and the like.

  A conventional induction heating cooker induces an object to be heated of aluminum, copper, or a material having a low or low permeability material (hereinafter referred to as a high conductivity material) having an electrical conductivity equivalent to or higher than these. A heating coil capable of being heated, and an electric conductor plate provided between the heating coil and the object to be heated, the electric conductor plate not covering the center of the heating coil or the vicinity thereof, and heating A slit or the like is provided so as to limit the distribution of the induced current that flows around in parallel with the direction in which the current flowing in the coil flows.

As a result of providing the electric conductor plate in this way, when heating an object to be heated made of a material having a high electrical conductivity, the equivalent series resistance of the heating coil becomes larger than when no electric conductor plate is provided, and the same output is obtained. In this case, the value of the current flowing through the heating coil can be reduced, and the buoyancy acting on the object to be heated can be shared by the electric conductor plate to reduce the buoyancy acting on the object to be heated. .
Furthermore, a slit or the like is provided so as to limit the distribution of the induced current flowing around the electric conductor plate, and the electric conductor plate is generated from the heating coil so as not to cover the center of the heating coil or the vicinity thereof. By concentrating the magnetic field as a magnetic field path linked to the object to be heated, a significant decrease in heating efficiency due to the attachment of the electric conductor is suppressed (for example, Patent Document 1).

Japanese Patent Laying-Open No. 2003-272812 (second page, FIG. 1)

However, the conventional induction heating cooker includes a heating coil capable of induction heating an object to be heated, and an electric conductor plate provided between the heating coil and the object to be heated, and the electric conductor plate is heated. Even if a slit or the like is provided so as not to cover the center of the coil or the vicinity thereof and to limit the distribution of the induced current flowing around the parallel to the direction of the current flowing through the heating coil, However, the heating distribution of the heating coil has a problem in that the central portion and the middle portion of the heating coil are high, while the heating of the peripheral portion is weak and uneven heating occurs. Further, it has been desired to further suppress the decrease in heating efficiency.
The present invention has been made to solve the above-described problems, and is used to heat a pan made of a high electrical conductivity material that reduces buoyancy acting on the pan, reduces heating unevenness, and suppresses a decrease in heating efficiency. A possible induction heating cooker is provided.

  An induction heating cooker according to the present invention includes a heating coil capable of induction heating a heated object made of aluminum, copper, or a low permeability material having an electric conductivity substantially equal to or higher than these, and a high-frequency current to the heating coil. Provided so as not to cover the central portion of the heating coil or the vicinity thereof between the inverter circuit to be supplied and the heating coil and the object to be heated, and has one or more slit portions extending from the outer diameter side to the inner diameter side An annular electric conductor plate, and the heating coil is divided into a plurality at intervals on the inner side and the outer side, and the annular electric conductor plate is also divided into a plurality at intervals on the inner side and the outer side. Above the gap between the heating coil positioned at least outside of the heating coil and the heating coil inside the heating coil, positioned at least outside of the divided annular electric conductor plate It is obtained so as to provide a gap between the annular electrical conductor plate positioned inside and than the annular electrical conductive plates.

  The present invention provides an annular electric conductor plate provided between a heating coil and an object to be heated so as not to cover the central portion of the heating coil or the vicinity thereof and having one or more slit portions extending from the outer diameter to the inner diameter. By reducing the buoyancy acting on the object to be heated and suppressing heating unevenness, the heating coil is divided into a plurality of parts at intervals between the inner side and the outer side, thereby reducing the heating unevenness and the annular electric conductor plate Is also divided into a plurality at intervals between the inner side and the outer side to suppress heating loss due to the provision of the annular electric conductor, and the heating coil positioned at least outside of the divided heating coils and the inner side thereof Above the gap with the heating coil, there is a gap between the annular electric conductor plate located at least outside of the divided annular electric conductor plates and the annular electric conductor plate located inside thereof. By kicking it, it is possible to further reduce the uneven heating.

Embodiment 1 FIG.
FIG. 1 is a circuit diagram showing a configuration of an induction heating cooker according to Embodiment 1 of the present invention, and FIG. 2 is a position of a heating coil, an annular electric conductor plate, an object to be heated, and a top plate temperature sensor of the induction heating cooker. FIG. 3 is a side view showing the relationship, FIG. 3 is a plan view showing a positional relationship between an example of the shape of the annular electric conductor plate of the induction heating cooker and the heating coil, and FIG. 4 is an inner heating coil and outer heating of the induction heating cooker. Explanatory diagram showing the direction of the induction current flowing in the high frequency current flowing in the coil and the inner annular electric conductor plate and the outer annular electric conductor plate, FIG. 5 is a reference diagram for explaining the temperature distribution of the pan bottom of the induction heating cooker 6 is explanatory drawing which shows the temperature distribution of the pan bottom of the induction heating cooking appliance, FIG. 7 is explanatory drawing which shows another example of a shape of the cyclic | annular electric conductor board of the induction heating cooking appliance.

In FIG. 1, a DC power supply circuit 2 that converts a commercial AC power supply 1 into a direct current includes a rectifier circuit 3, a choke coil 4, and a smoothing capacitor 5.
An inverter circuit 6 is connected to the output side of the DC power supply circuit 2 for converting DC power output from the DC power supply circuit 2 into high-frequency power.
The inverter circuit 6 includes switching elements 7 and 8 connected in series between DC buses, antiparallel diodes 9 and 10 connected in reverse parallel to the switching elements 7 and 8, and switching elements 7 and 8, respectively. The drive circuit 11 is turned on / off alternately. A resonance circuit 12 is connected to the output side of the inverter circuit 6.
The resonance circuit 12 is constituted by a series circuit of an internal heating coil 13 and an external heating coil 14, which are heating coils divided inward and outward, and a resonance capacitor 15.
The inner heating coil 13 and the outer heating coil 14 are made up of an inner annular electric conductor plate 16 which is an annular electric conductor plate, an outer annular electric conductor plate 17 and a pan 19 which is an object to be heated placed on the top plate 18 and a magnetic field. Are connected.
The pan 19 as the object to be heated is made of aluminum, copper, or a material having a low magnetic permeability (hereinafter referred to as a high electric conductivity material) equal to or lower than that of aluminum or copper.

A top plate 18 is disposed above the inner heating coil 13 and the outer heating coil 14, and a top plate temperature sensor 20 such as a thermistor is provided on the lower surface of the top plate 18 to detect the temperature of the pan via the top plate 18. To do.
The input current detection means 21 that detects the input current from the commercial AC power supply 1 is connected to the control means 22 that controls the entire induction heating cooker.
The control means 22 controls the drive circuit 11 based on the detection value of the input current detection means 21 to perform thermal power control, and controls the temperature of the pan 19 based on the temperature detected by the top board temperature sensor 20.
Since the annular electric conductor plates 16 and 17 are self-heated by the induced current, the top plate temperature sensor 20 is disposed in the gap between the inner annular conductor plate 16 and the outer annular conductor plate 17 in order to avoid the influence. It is disposed closer to the inner annular conductor plate 16.

As shown in FIGS. 2 and 3, the inner heating coil 13 and the outer heating coil 14 divided into two parts are connected in series as shown in FIG.
Four substantially rectangular parallelepiped rod-shaped ferrites 23 are radially arranged on the lower surfaces of the inner heating coil 13 and the outer heating coil 14 with respect to the coil center.
Further, an inner annular electric conductor plate 16 and an outer annular electric conductor plate 17 which are electric conductor plates divided into two parts are arranged on the upper surface side of the inner heating coil 13 and the outer heating coil 14, and these inner annular electric conductor plates 17 are arranged. A top plate 18 on which a pot 19 for an object to be heated is placed is disposed above 16 and the outer annular electric conductor plate 17.
Accordingly, the gap between the inner annular electric conductor plate 16 and the outer annular electric conductor plate 17 is positioned above the gap between the inner heating coil 13 and the outer heating coil 14.

Therefore, the magnetic field generated by the high-frequency current flowing through the inner heating coil 13 and the outer heating coil 14 is magnetically shielded by the ferrite 23 on the lower surface side of the inner heating coil 13 and the outer heating coil 14, and the inner annular electric conductor plate 16 on the upper surface side. The outer annular electrical conductor plate 17 and the pan 19 are linked to generate an induced current.
As shown in FIGS. 3 and 4, the inner annular electric conductor plate 16 arranged on the upper surface side of the inner heating coil 13 and the outer annular electric conductor plate 17 arranged on the upper surface side of the outer heating coil 14, respectively, Slit portions 16a and 17a are provided from the diameter to the inner diameter, and an induction current that circulates around the center of the inner heating coil 13 and the outer heating coil 14 cannot flow.

Next, the operation | movement in the induction heating cooking appliance of Embodiment 1 of this invention is demonstrated.
As shown in FIGS. 1 and 3, the inner heating coil 13 and the outer heating coil 14 are connected in series. When a high-frequency current is simultaneously supplied from the inverter circuit 6, a high-frequency magnetic field is generated by the high-frequency current. The high-frequency magnetic field interlinks with the inner annular electric conductor plate 16, the outer annular electric conductor plate 17, and the pot 19 that is the object to be heated to generate an induced current.
FIG. 4 shows the direction of the coil current flowing through the inner heating coil 13 and the outer heating coil 14 (solid arrow) and the direction of the induced current flowing through the inner annular electric conductor plate 16 and the outer annular electric conductor plate 17 (broken arrow). Yes.
Although the coil currents flowing through the inner heating coil 13 and the outer heating coil 14 flow in opposite directions at high frequencies, they flow in the clockwise direction at the time shown in FIG. 4, and the inner annular electric conductor plate 16 and the outer annular electric conductor plate 17, the magnetic flux generated by the high-frequency current flowing in the inner heating coil 13 and the outer heating coil 14 is linked, and an induced electromotive force is generated in the direction opposite to the current flowing in the heating coil.

However, the inner annular electric conductor plate 16 and the outer annular electric conductor plate 17 are provided with slit portions 16a and 17a, and an annular current in a reverse circuit direction with respect to the current flowing through the inner heating coil 13 and the outer heating coil 14 is provided. The flow is hindered.
Here, the induced voltage generated at both ends of the slit portions 16a, 17a is higher on the outer diameter side of each electric conductor plate because the diameter is larger than the inner diameter side and the path is longer. In each of the annular electric conductor plates 17, the induced electromotive force generated at both ends of the slit portions 16 a, 17 a has a relatively lower voltage generated on the inner diameter side than the outer diameter side. An induced current flows in the opposite direction to the current flowing in the heating coil on the outer diameter side, and an induced current flows in the same direction as the current flowing in the heating coil on the inner diameter side.

  As a result, a part of the magnetic field interlinked with the inner annular electric conductor plate 16 and the outer annular electric conductor plate 17 is detoured to the outside of the electric conductor plate (particularly on the inner diameter side) by the induced current flowing through each electric conductor plate, and is induced. It is consumed as a resistance loss of current, and part of it passes through the electric conductor plate and reaches the pan of the object to be heated, and the slit portions 16a and 17a of the inner annular electric conductor plate 16 and the outer annular electric conductor plate 17 and the inner and outer portions In a portion where there is no electric conductor plate such as a gap between the annular electric conductor plates 16 and 17, the magnetic field generated by the current flowing in the heating coil reaches the pot 19 without much influence of the electric conductor plate. The magnetic flux that bypasses the plate reaches the pan 19 and generates an induced current to heat it.

Therefore, a high frequency magnetic field is strengthened in the vicinity of the inner side of the outer annular electric conductor plate 17 in the gap between the inner annular electric conductor plate 16 and the outer annular electric conductor plate 17.
The high frequency magnetic field affects the thermistor, lead wire portion and the like constituting the top plate temperature sensor 20 and affects the detection temperature. Therefore, the top plate temperature sensor 20 is connected to the outer annular conductor plate 17 in order to suppress the influence of the high frequency magnetic field. By disposing at a position close to the inner annular conductor plate 16, it is avoided that a magnetic field bypassing the annular electric conductor plate greatly affects the top plate temperature sensor 20.

  FIG. 5 is a reference diagram for explaining the temperature distribution of the pan bottom of the induction heating cooker according to the first embodiment of the present invention, in which (a) and (b) are heated by the heating coil 24 that is not divided into the inside and the outside. 2 shows the temperature distribution (heating distribution) of the pot bottom, and (c) shows the temperature distribution (heating distribution) of the pot bottom when heated by the heating coils 13 and 14 divided inside and outside. FIG. 6 is an induction heating cooker according to Embodiment 1 of the present invention, and shows the temperature distribution at the bottom of the pan when there are heating coils divided inside and outside and an annular electric conductor plate is provided.

When the heating coil 24 shown in FIG. 5A is not divided into the inside and outside and the annular electric conductor plate 25 is not provided, the temperature distribution of the pot bottom is such that the pot bottom portion facing the substantially central portion of the heating coil winding has a donut shape. However, the temperature of the heating coil central portion where the heating coil winding does not exist and the temperature of the outer periphery of the heating coil become lower, and the heating unevenness increases.
The temperature distribution at the bottom of the pot when the annular electric conductor plate 25 is provided without dividing the heating coil 24 shown in FIG. 5 (b) into the inside and outside is part of the magnetic flux interlinked with the annular electric conductor plate 25. Since the detour is caused by the induced current flowing through the conductor plate 25, the temperature of the pan bottom facing the substantially central portion of the heating coil winding that becomes high temperature is suppressed, and the temperature of the pan bottom facing the central portion of the heating coil is raised to cause temperature unevenness. Although improved, the bottom temperature of the outer periphery of the heating coil is low and not sufficient.

  In addition, the heating coil shown in FIG. 5C is divided into the inside and outside, and the temperature distribution of the pan bottom when the annular electric conductor plate is not provided is the divided inner heating coil 13 and outer heating coil 14. The pan bottom portion facing the substantially central portion of each winding becomes hot like a donut, and the temperatures of the center portion of the inner heating coil 13, the gap between the inner and outer heating coils 13 and 14, and the outer peripheral portion of the outer heating coil 14 are increased. However, the temperature difference is small compared to the heating distribution (FIG. 5A) by the heating coils that are not divided, and the pan bottom positions at which the temperature peaks are dispersed.

  Furthermore, the temperature distribution of the bottom of the pan when the annular electric conductor plate of the induction heating cooker according to the first embodiment of the present invention shown in FIG. 6 is provided is such that the annular electric conductor plate corresponds to the inner heating coil 13 and the outer heating coil 14. Since the inner annular electric conductor plate 16 and the outer annular electric conductor plate 17 are disposed so that the gap portion is positioned above the gap portion between the inner heating coil 13 and the outer heating coil 14, the inner annular electric conductor plate 16 is disposed. Since the magnetic field bypassing the outer annular electrical conductor plate 17 moves to the gap between the inner annular electrical conductor plate 16 and the outer annular electrical conductor plate 17, the magnetic field bypassing the outer annular electrical conductor plate 17 moves to the center portion of the heating coil. The temperature of the hot part of the pan bottom facing the approximately central part of the wire and the outer heating coil winding is suppressed, and the temperature of the gap part of the inner and outer heating coils as well as the center part of the heating coil is increased to further reduce heating unevenness. ing

In addition, in the slit portions 16a and 17a provided in the inner annular electric conductor plate 16 and the outer annular electric conductor plate 17, no induced current can be generated there, and there is no heat loss in the annular electric conductor plate. Since the passing magnetic field is not hindered, the heating of the pan bottom is stronger than the portion where the annular electric conductor plate exists.
Therefore, by arranging the direction in which the slit portion is provided from the center portion of the heating coil in different directions in the inner annular electric conductor plate 16 and the outer annular electric conductor plate 17, it is possible to further reduce the heating unevenness of the pan bottom.

Moreover, in the said Embodiment 1, although the slit part 16a, 17a of the inner annular electric conductor board 16 and the outer annular electric conductor board 17 was each shown as an example, (a), (b) of FIG. As shown in FIG. 2, the slit portions 16a and 17a may be two or more.
FIG. 7A shows an example of two slit portions 16a and 17a, and FIG. 7B shows an example of four slit portions 16a and 17a.
Thus, since the ratio that the magnetic field reaches the pan increases without being obstructed by the electric conductor plate when the number of the portions where the slit portions 16a and 17a are provided is increased, it is possible to suppress a decrease in heating efficiency. (Heating) Since the effect of improving the temperature distribution is also suppressed, it is desirable to select an appropriate number of slits based on actually measured data when the pan is heated.

Embodiment 2. FIG.
8 is a side view showing the dimensional relationship between the heating coil and the annular electric conductor plate of the induction heating cooker according to Embodiment 2 of the present invention, and FIG. 9 is the dimension of the heating coil and the annular electric conductor plate of the induction heating cooker. FIG. 10 is a side view showing another dimensional relationship between the heating coil and the annular electric conductor plate of the induction heating cooker, and FIG. 11 shows the difference between the heating coil and the annular electric conductor plate of the induction heating cooker. It is a top view which shows these dimensional relationships.
In the first embodiment, the inner annular electric conductor plate 16 and the outer annular electric conductor plate 17 are disposed so as to substantially cover the inner heating coil 13 and the outer heating coil 14, respectively. 8 and 9, the outer diameters of the inner annular electric conductor plate 16 and the outer annular electric conductor plate 17 are smaller than the outer diameters of the inner heating coil 13 and the outer heating coil 14, respectively.

Thus, the inner heating coil 13 and the outer heating coil 17 are formed such that the outer diameters of the inner annular electric conductor plate 16 and the outer annular electric conductor plate 17 are smaller than the outer diameters of the inner heating coil 13 and the outer heating coil 14, respectively. 14 is weakened in the vicinity of the outer diameter of the inner heating coil 13 and the outer heating coil 14 by the induction current flowing in the outer diameter portions of the inner annular electric conductor plate 16 and the outer annular electric conductor plate 17. Therefore, uneven heating can be further reduced.
Further, as shown in FIGS. 10 and 11, only the outer diameter of the outer annular electric conductor plate 17 may be smaller than the outer diameter of the outer heating coil 14. In this case, it is possible to suppress a decrease in the pot bottom heating distribution in the vicinity of the outer diameter of the outer heating coil 14 that is the outermost part of the heating coil.

Embodiment 3 FIG.
FIG. 12 is an explanatory view showing an example of the shape of the annular electric conductor plate of the induction heating cooker according to Embodiment 3 of the present invention and an arrangement example of the top plate temperature sensor, and (a) is a slit portion of each annular electric conductor plate. Is an example of one place, and (b) shows an example of four slit portions of each annular electric conductor plate.
In the first and second embodiments, the annular electric conductor plate is divided into the inner and outer parts, and in this third embodiment, as shown in FIGS. 12 (a) and 12 (b), the inner annular electric conductor plate is separated. 16 and the outer annular electric conductor plate 17 are connected to each other by providing a connecting portion 26.

As in the third embodiment, the inner annular electric conductor plate 16 and the outer annular electric conductor plate 17 are coupled and fixed by the connecting portion 26, so that the number of parts is reduced from two to one, and parts management and assembly are performed. Becomes easy.
Furthermore, in comparison with the case where the inner annular electric conductor plate 16 and the outer annular electric conductor plate 17 are assembled as individual parts without being connected, the inner annular electric conductor plate 16 and the outer annular electric conductor plate 17 are used in the third embodiment. Are coupled and fixed by the connecting portion 26, the distance between the inner annular electric conductor plate 16 and the outer annular electric conductor plate 17 can be kept constant, and the variation in heating distribution can be reduced. .
Further, the top plate temperature sensor 20 is arranged at a position away from the connecting portion 26 provided between the inner and outer annular electric conductor plates 16 and 17, for example, in FIG. It arrange | positions in the position of 20a-20c, and in FIG.12 (b), the two top-plate temperature sensors 20 are arrange | positioned in the position of 20d-20e.
Thus, by arranging the top plate temperature sensor 20 at a position away from the connecting portion 26, the influence of a magnetic field that bypasses the connecting portion 26 can be avoided.

Embodiment 4 FIG.
FIG. 13: is a circuit diagram which shows the structure of the induction heating cooking appliance concerning Embodiment 4 of this invention.
In the fourth embodiment, the same configurations as those in the first embodiment are denoted by the same reference numerals, and the description of the overlapping configurations is omitted.
In the first to third embodiments, an example in which the divided inner heating coil 13 and the outer heating coil 14 are connected in series and the inverter circuit 6 that allows high-frequency current to flow simultaneously to the inner and outer heating coils is shown. In the fourth embodiment, as shown in FIG. 13, the inner heating coil 13 and the outer heating coil 14 are connected in parallel, connected to the connection point of the switching elements 7 and 8, and operated by the control means 22. The circuit configuration is such that either the inner heating coil 13 or the outer heating coil 14 is selected and a high-frequency current flows.

Also in the case of the fourth embodiment, the heating coil selection switch 27 has the inner annular electric conductor plate 16 and the outer annular electric conductor plate 17 to reduce the buoyancy acting on the pan and to pass the high frequency current through the heating coil. By switching to the inner heating coil 13 and the outer heating coil 14, cooking that changes the heating distribution of the pan bottom is possible.
Further, since the electric conductor plate is divided into the inner annular electric conductor plate 16 and the outer annular electric conductor plate 17, the case where a high frequency current is passed through the inner heating coil 13 and the case where a high frequency current is passed through the outer heating coil 14. Induction current flows through different annular electrical conductor plates, and the magnetic field that bypasses the annular electrical conductor plate also passes through different locations (near the center of the heating coil and between the inner and outer heating coils), so there is a cooking function that heats different positions on the pan bottom It is not disturbed by the annular electrical conductor plate.

Embodiment 5 FIG.
FIG. 14 is a circuit diagram showing a configuration of an induction heating cooker according to Embodiment 5 of the present invention.
In the fifth embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description of the overlapping components is omitted.
In this Embodiment 5, as shown in FIG. 14, although the divided | segmented inner heating coil 13 and the outer heating coil 14 are connected in series, according to the pan diameter to be used, a high frequency current is made into the inner heating coil 13 and This is a circuit configuration example that can be switched between energizing the outer heating coil 14 simultaneously and energizing only the inner heating coil 13.
By connecting a bypass switch 28 operated by the control means 22 in parallel with the external heating coil 14 and opening the bypass switch 28, the internal heating coils 13 and 14 are energized simultaneously, and the bypass switch 28 is closed. By setting the state, only the inner heating coil 13 is energized.

In the fifth embodiment, the large-diameter pan is opened by setting the bypass switch 28 in an open state, and a high-frequency current is simultaneously supplied to the inner heating coils 13 and 14 so that a part of the generated magnetic field is absorbed. The buoyancy acting on the pan is reduced by bypassing the annular electric conductor plate 16 and the outer annular electric conductor plate 17 and temperature unevenness of the pan bottom is suppressed.
On the other hand, a part of the generated magnetic field is bypassed by the inner annular electric conductor plate 16 by causing the high-frequency current to flow only through the inner heating coil 13 by closing the bypass switch 28 for the small-diameter pan. This can reduce the buoyancy acting on the pan and improve the temperature unevenness of the pan bottom.
Moreover, since the bypass distance of a magnetic field becomes short compared with the case where the cyclic | annular electric conductor board which is not divided | segmented inside and outside is used, the fall of the heating efficiency by providing an annular electric conductor board can be suppressed.

Embodiment 6 FIG.
FIG. 15 is a side view showing an example of the positional relationship among a heating coil, an annular electric conductor plate, an object to be heated, and a top plate temperature sensor of an induction heating cooker according to Embodiment 6 of the present invention, and FIG. 16 shows the induction heating cooking. It is a side view which shows another example of the positional relationship of the heating coil of a container, a cyclic | annular electrical-conductor board, a to-be-heated object, and a top-plate temperature sensor.
In the sixth embodiment, as shown in FIG. 15, the inner heating coil 13, the inner heating coil 29, the outer heating coil 14, and the inner annular electric conductor in the case where the heating coil and the electric conductor plate are divided into three inside and outside, respectively. An arrangement example of the plate 16, the middle annular electric conductor plate 30, and the outer annular electric conductor plate 17 is shown.
Also, as shown in FIG. 16, the heating coil is divided into three inside and outside to form an inner heating coil 13, an intermediate heating coil 29, and an outer heating coil 14, and the annular electric conductor plate is divided into two inside and outside, An arrangement example in which the annular electric conductor plate 16 and the outer annular electric conductor plate 17 are shown is shown.

In the sixth embodiment, the number of inner and outer divisions of the heating coil and electric conductor plate is three, and the inner heating coil 13, the intermediate heating coil 29, the outer heating coil 14, the inner annular electric conductor plate 16, and the intermediate annular electric conductor plate 30. By using the outer annular electric conductor plate 17, it is possible to disperse the heat generation distribution of the object to be heated and move the magnetic field to the center portion of the heating coil or the gap portion of the heating coil, thereby further reducing the temperature unevenness.
Further, the heating coil divided into three is divided into less than the number of heating coil inner and outer divisions with two electric conductor plates inside and outside to form an inner heating coil 13, an intermediate heating coil 29, and an outer heating coil 14. Even when the conductor plate 16 and the outer annular electric conductor plate 17 are used, the heat distribution of the object to be heated is dispersed and the heating at the center portion of the heating coil and the heating coil gap facing the heating coil gap is strengthened. Can be reduced.
Of course, even if the number of inner and outer divisions of the heating coil and the electrical conductor plate is 3 or more, the same effect as described above is obtained.
Of course, when the electric conductor plate is divided into two or more inside and outside and less than the number of divisions inside and outside the heating coil with respect to the heating coil divided into three or more, the same effect as described above is obtained.

The circuit diagram which shows the structure of the induction heating cooking appliance which concerns on Embodiment 1 of this invention. The side view which shows the positional relationship of the heating coil of the same induction heating cooking appliance, a cyclic | annular electrical conductor board, a to-be-heated object, and a top-plate temperature sensor. The top view which shows the positional relationship of an example of the shape of the cyclic | annular electrical conductor board of the same induction heating cooking appliance, and a heating coil. Explanatory drawing which shows the direction of the high frequency current which flows into the inner heating coil and the outer heating coil of the induction heating cooking appliance, and the induction current which flows into an inner annular electric conductor plate and an outer annular electric conductor plate. The reference figure for demonstrating the temperature distribution of the pan bottom of the induction heating cooking appliance. Explanatory drawing which shows the temperature distribution of the pan bottom of the same induction heating cooking appliance. Explanatory drawing which shows another example of a shape of the cyclic | annular electric conductor board of the same induction heating cooking appliance. The side view which shows the dimensional relationship of the heating coil of the induction heating cooking appliance which concerns on Embodiment 2 of this invention, and a cyclic | annular electrical conductor board. The top view which shows the dimensional relationship of the heating coil of the same induction heating cooking appliance, and a cyclic | annular electrical conductor board. The side view which shows another dimensional relationship of the heating coil of the same induction heating cooking appliance, and a cyclic | annular electrical conductor board. The top view which shows another dimensional relationship of the heating coil of the same induction heating cooking appliance, and a cyclic | annular electrical conductor board. Explanatory drawing which shows the example of a shape of the cyclic | annular electrical conductor board of the induction heating cooking appliance concerning Embodiment 3 of this invention, and the example of arrangement | positioning of a top-plate temperature sensor. The circuit diagram which shows the structure of the induction heating cooking appliance which concerns on Embodiment 4 of this invention. The circuit diagram which shows the structure of the induction heating cooking appliance which concerns on Embodiment 5 of this invention. The side view which shows an example of the positional relationship of the heating coil of the induction heating cooking appliance which concerns on Embodiment 6 of this invention, a cyclic | annular electrical conductor board, a to-be-heated object, and a top-plate temperature sensor. The side view which shows another example of the positional relationship of the heating coil of the same induction heating cooking appliance, a cyclic | annular electrical conductor board, a to-be-heated object, and a top-plate temperature sensor.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Commercial AC power supply, 2 DC power supply circuit, 6 Inverter circuit, 7, 8 Switching element, 9, 10 Reverse parallel diode, 11 Drive circuit, 12 Resonance circuit, 13 Inner heating coil, 14 Outer heating coil, 15 Resonance capacitor, 16 Inner annular electric conductor plate, 17 Outer annular electric conductor plate, 18 Top plate, 19 pan, 20 Top plate temperature sensor, 22 Control means, 23 Ferrite.

Claims (10)

A heating coil capable of inductively heating an object to be heated made of a low magnetic permeability material having an electrical conductivity substantially equal to or higher than aluminum or copper; and
An inverter circuit for supplying a high-frequency current to the heating coil;
An annular electrical conductor plate provided between the heating coil and the object to be heated so as not to cover the central portion of the heating coil or the vicinity thereof and having one or more slit portions extending from the outer diameter side to the inner diameter side. Prepared,
The heating coil is divided into a plurality at intervals between the inside and the outside,
The annular electrical conductor plate is also divided into a plurality at intervals on the inside and outside,
An annular electric conductor located at least outside of the divided annular electric conductor plate above a gap between the heating coil located at least outside of the divided heating coils and a heating coil inside thereof. An induction heating cooker characterized in that a gap is provided between a plate and an annular electric conductor plate located inside thereof.   Of the annular electric conductor plates divided into a plurality, the outer diameter of the annular electric conductor plate located at least outside is located at least outside of the heating coils located below the annular electric conductor plates. The induction heating cooker according to claim 1, wherein the heating coil is smaller than the outer diameter of the heating coil.   The induction heating cooker according to claim 1 or 2, wherein the slit portions of the divided annular electric conductor plates are arranged in different directions when viewed from the center of the heating coil.   It is provided with a top plate temperature detecting means for detecting the temperature of the top plate on which the object to be heated is placed, and the top plate temperature detecting means is arranged in a gap portion of the annular electric conductor plate divided into a plurality of parts. The induction heating cooker according to any one of claims 1 to 3.   The induction heating cooker according to any one of claims 1 to 3, wherein a connecting portion that connects the divided annular electric conductor plates is provided.   A top plate temperature detecting means for detecting the temperature of the top plate on which the object to be heated is placed is provided, and the top plate temperature detecting means is a gap portion of the annular electric conductor plate divided into a plurality of positions separated from the connecting portion. The induction heating cooker according to claim 5, wherein the induction heating cooker is arranged.   The said top plate temperature detection means is arrange | positioned in the position close | similar to the cyclic | annular conductor board located inside from the outer side among the gap | interval parts of the divided | segmented cyclic | annular conductor board. Induction heating cooker.   The induction heating cooker according to any one of claims 1 to 7, wherein the heating coils divided into a plurality are connected in series.   The plurality of divided heating coils are connected in series, and each of the other divided coils excluding the innermost divided coil is energized to the coil at the time of opening, and the coil is not connected to the coil at the time of closing. The induction heating cooker according to any one of claims 1 to 7, further comprising a bypass switch for energization.   8. The heating coil selection switch according to claim 1, further comprising a heating coil selection switch that connects the plurality of divided heating coils in parallel and selectively energizes the divided heating coils. 9. Induction heating cooker.

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